<Chinese TV Series NOW> ”Kyouhyo -End of the Beginning-” 3EP3, police reinvestigating the incident from 7 years ago = Synopsis / Spoilers

※This article contains spoilers and synopsis.
Episode 3 of "Beginning-3" depicts the police re-investigating the incident from seven years ago.
An Changlin asks An Xin to investigate the power company to find a breakthrough in the 228 shooting incident.
At that time, Lu Han, a detective, was also investigating the case, but disappeared. Lu Han tracked down Gao Xiaochen using information about the attacker's motorcycle.
After that, they searched Gao Qiqiang's house and found that Gao Xiaochen's car had been sent to a repair shop. Lu Han strengthened his suspicions about Gao Xiaochen, but in the end he was unable to find any evidence.
Gao Qiqiang informed Gao Xiaochen that the investigation into the 228 shooting incident had been reopened and ordered him to be careful with his words and actions. Meanwhile, An Xin headed to Lishui County, where Lu Han was last seen, to investigate the situation.
I decided to investigate.